The present invention relates generally to self-aligning bearings having a ball-like inner member with a convex outer surface and an outer member having an inner surface with a complementary concave spherical inner face. These types of bearings, which are commonly called "spherical bearings," have been utilized in industry for a substantial period of time. The technological evolution of these type bearings has been directed more in the terms of material composition of its various component parts rather than toward basic changes in design concepts. Accordingly, the design advances in spherical bearings have not been substantial in nature and thereby presently limit their applications.
One area in which the spherical bearings have been extensively applied is high temperature applications. This is due to the spherical bearing self-aligning characteristic and the relative ruggedness of this type bearing. A typical such application is marrying of a spherical bearing to a valve actuator for a butterfly valve in a high pressure high temperature (e.g. 1000.degree.F) steam system. In this application the outer race is commonly press-fitted or otherwise attached to actuator control linkage in a remote inaccessible area rendering it difficult to remove and/or maintain. When any such maintenance is required, such as replacing of the ball, the entire bearing assembly including the inner and outer race member would have to be removed and replaced by an entirely new bearing assembly. Such an operation could entail substantial expense and down time of the entire steam system.
There are a number of prior art type spherical bearings which have been addressed to this kind of problem. One such type prior art bearing is the "messerschmidt" bearing. A concept of this bearing is that the ball can be removed in the field without disassembling the entire bearing, that is, removing the outer race member from its mounting.
One may refer to my prior invention in this general field as embodied in U.S. Pat. No. 3,365,249, Patented Jan. 23, 1968 and entitled "Spherical Bearing." This particular bearing may be disassembled in the field but does not include the provision of changing the inner surface of the outer member. This area can become particularly vulnerable to damage, corrosion, wear and the like in high temperature applications.